There exist numerous circumstances under which a person would want to have a simple, battery operated, rugged, efficient, color selectable and very portable light source for purposes of signaling others of his or her presence under visually adverse conditions. Such conditions could include locating someone in a dark, smoke-filled room, signaling oncoming drivers of a road emergency, signaling search and rescue personnel if a carrier of the signaling light source becomes lost in the wilderness, signaling drivers of the carrier's presence while riding a bicycle, etc. Of particular interest is the application in a smoke-filled room as often encountered by firefighters and support personnel responding to a building fire, especially under self contained breathing apparatus (“SCBA”) conditions.
When firefighting personnel spray water on flames in a burning room, it is quite common for the room to quickly become pitch black and filled with dense smoke, making visibility nearly impossible. If a searcher is using a flashlight or other directed light source, the light must travel from the searcher to personnel and return back to the searcher to visually locate personnel. Even a very intense light source penetrates a short distance through dense smoke. Additionally, the diffusion of the light caused by the smoke tends to obscure the light returning from personnel since diffusive back-glow of light is greatest near the source.
If firefighting personnel carry or wear a light source, the optical path length between personnel and a searcher is cut in half. Also, since the searcher is not using his or her own light source, there is no back-glow to obscure personnel's light, making location possible at a much greater distance. By putting the signaling light source on personnel, the searcher has the additional visual cue of increased luminous intensity to help locate the personnel.
In addition to rapidly locating personnel in a dense smoke environment, searchers also need to rapidly discern as much as possible about the personnel's identity. Having the ability to preset a color code for individual personnel prior to entering a burning building subsequently provides searchers with additional early stage identification information.
Experimental testing in dense smoke-filled rooms establishes that light of a particular color is more visible in a smoky environment than other colors. Consequently, a signaling light source emitting a color of light that is more visible in a smoky environment increases the likelihood of locating firefighters under such circumstances.
A firefighter's signaling light source must be extremely durable, reliable, water and temperature resistant and should provide long battery life. Also, firefighting equipment must be easily cleaned after a fire, typically with solvents or strong detergents. Therefore, any potentially sensitive components included in a signaling light source need to be well isolated from such environmental conditions.
Disclosure
An object of the present disclosure is to provide a signaling light source that penetrates smoke well.
Another object of the present disclosure is to provide a signaling light source that is visible over a very wide angle.
Another object of the present disclosure is to provide a signaling light source that resists damage through exposure to harsh user environments.
Another object of the present disclosure is to provide a signaling light source that permits rapidly identifying individual personnel.
Briefly, in one aspect disclosed herein is a signaling light source particularly adapted for facilitating locating personnel under adverse conditions such as in a smoky environment. The disclosed signaling light source also resists damage from exposure to a harsh user environment. The signaling light source includes a hollow, translucent environmental isolation tube that encloses a light distributing rod. The light distributing rod has a diffusive light-pipe. Reflective end caps included in the signaling light source:                1. mate with open ends of the environmental isolation tube; and        2. with opposite ends of the light-pipe,for sealing the light distributing rod within the environmental isolation tube. At least one of the end caps is juxtaposable with a light source which when energized emits light into the light-pipe of the light distributing rod for reemission from the light-pipe.        
Briefly, in another aspect disclosed herein is a lighting unit particularly adapted for facilitating locating personnel under adverse conditions such as in a smoky environment. The lighting unit includes at least one, and preferably two, of the disclosed signaling light sources. The lighting unit further includes at least one personnel identifying red-green-blue (“RGB”) light emitting diode (“LED”) that emits a selectable color of light for uniquely identifying personnel in a smoky environment.
Briefly, in yet another aspect disclosed herein is a method for energizing operation of a LED light source included in the signaling light source. The method for energizing operation of the LED light source includes the step of supplying a sequence of electrical current pulses to the LED. The electrical current pulses supplied to the LED repeat at sufficiently long intervals of time so that light emitted by the signaling light source pulses visually. Visual pulsing of light emitted by the signaling light source:                1. facilitates a searcher's ability to visually locate personnel; and        b. reduces electrical power required for operating the signaling light source.        
Briefly, in even yet another aspect disclosed herein is another method for energizing operation of at least a pair of LED light sources each of which is preferably respectively included in a signaling light source. This second method for energizing operation of the LED light sources includes the steps of:                1. supplying electrical current for energizing operation of the light sources from at least one battery;        2. monitoring battery operating condition;        3. while battery operating condition remains adequate for energizing operation of series connected light sources, connecting the LEDs in series; and        4. when battery operating condition becomes inadequate for energizing operation of series connected light sources, connecting the LEDs in parallel.This second method for energizing operation of a pair of LED light sources extends the battery energized operating interval of signaling light sources.        
Briefly, in a final aspect disclosed herein is yet another method for energizing operation of a LED light source included in a signaling light source. This third method for energizing operation of the LED light source includes the steps of:                1. monitoring smoke density in environment around the signaling light source;        2. when smoke density monitored in environment around the signaling light source indicates dense smoke, increasing energy supplied to the LED light source; and        3. when smoke density monitored in environment around the signaling light source indicates sparse smoke, decreasing energy supplied to the LED light source.This third method for energizing operation of light sources reduces average electrical power required for operating the signaling light source.        
The present invention advantageously places a LED light source and drive electronics inside protective enclosures, and transfers light emitted by the light source into a severe surrounding environment via a signaling light source. The signaling light source is made from extremely durable materials and withstands both the operational environment and clean-up.
The present invention further facilitates rapidly identifying individual personnel while maximizing the distance at which personnel are locatable by separating the location light unit into a color selectable section and a constant color section.
These and other features, objects and advantages will be understood or apparent to those of ordinary skill in the art from the following detailed description of the preferred embodiment as illustrated in the various drawing figures.